__Set traveler time (Tf-To) to 2 years, initial proper velocity uo to 0 ly/y, and acceleration to 1.03 ly/yy (approx, 1g; alternatively input ao as 9.8 m/ss before switching to ly and y). Final proper velocity is 3.86 ly/y (3.86 times the speed of light!), while the distance traveled is 2.68 lightyears.,
__The 3D and VvsT views are especially informative here, because you can see how the traveler's (magenta) speed increases much more rapidly than would have been expected from the Newtonian calculation (yellow), while the observer who stays at home (cyan) sees the traveler speed leveling off at the speed of light.,
__The real message of Einstein's theory of special relativity was not that we can't travel from point A to point B at rates better than 1 ly/y, but that different observers (according to their velocities) experience time moving by at different rates. Hence in this program we denote time with t, T and b so that the various ways to see events can coexist with minimal confusion.